Detection circuit, power circuit, and luminaire

According to one embodiment, a detection circuit including first and second comparators and a determining unit is provided. The first comparator includes a first input terminal for inputting a first detection voltage, a second input terminal for inputting a first threshold voltage, and a first output terminal configured to output a first output signal. The second comparator includes a third input terminal for inputting a second detection voltage, a fourth input terminal for inputting a second threshold voltage higher than the first threshold voltage, and a second output terminal configured to output a second output signal. The determining unit is configured to determine the presence or absence of conduction angle control of an AC voltage and whether the conduction angle control is a phase control system or an opposite phase control system on the basis of a time difference between the first output signal and the second output signal.